For many years various public utilities, public transportation companies and other organizations that use a highly mobile fleet of service personnel have dispatched orders to those personnel via wireless radio or cellular phone calls. Such dispatch systems are expensive because they tend to be smaller than public systems and thus use equipment that is manufactured in small volumes, which eliminates economies of scale. Likewise, such systems often involve creating an expensive private network from scratch. On the other hand, public wireless telecommunication networks, including cellular and PCS, have recently become far more ubiquitous, feature rich and cost effective. Those systems have not, until recently, provided the type of messaging capability best suited for managing dispatch operations.
That has changed with the advent of SMS services. SMS (or Short Message Service) is part of the Global System for Mobile communications (GSM) digital standard, originally only at 900 MHz but later also at 1800 MHz (also known as DCS 1800), 1900 MHz (also known as PCS 1900) and 800 MHz (E-GSM). SMS provides the ability to send and receive short messages of up to 160 characters of text through a mobile terminal, or cell phone. The SMS service functions similarly to two-way paging, but it is rapidly evolving into an electronic messaging (“e-mail”) system. With the appropriate software, users may send, receive, and forward messages from a personal computer (PC) to single addressees, or groups of addressees. These SMS messages are managed by the user's telephone Service Center in a “store and forward” manner, similar to e-mail, such that delivery is guaranteed. Thus, when the target telephone is unavailable due to being out of service area, etc., the network will hold the message and deliver it shortly after the phone comes back into range. The message can be sent by a central paging service, or by a compatible handset.
Not all digital phones are capable of transmitting SMS messages, but most current digital phones can receive them, as long as the network operator has the facility enabled. The SMS message text may be keyed into the mobile phone using the phone's keypad, and with some telephone models, through a full QWERTY keyboard with which the model is adapted to interface.
Under the GSM protocol each network provides one or more Service Centers, and each of these can send to any GSM mobile on any network. These Service Centers (“SC”) provide a store-and-forward SMS function, which holds the message until it can be delivered or until a SMSC timeout occurs. In SMS operation, a user may enter a correspondent's (or addressee's) mobile number, type a message, and forward the message to the user's SC. The SC address is normally stored in the phone and/or SIM card. The cellular exchange routes the SMS message in an SCCP packet within the GSM's TDMA frame format. International SCCP messages are routed based on a Global Title. The Global Title used for SMS is the Service Center address. The SCCP packet is passed from exchange to exchange until it reaches the destination Service Center. Each exchange along the route inspects the Global Title and uses this to route the message to the next exchange in the chain.
Once the message is received at the correspondent's SC, the addressed center sends back a confirmation in a return SCCP packet, either directly to the user's SMSC or to the nearest exchange, and the confirmation is routed in similar fashion back to the original cellular exchange and on to the user's mobile unit. When a message is received by the phone, it will be stored in the SIM (subscriber identity module) smart card, and will be available to be read whenever needed. It will be saved until you delete it, allowing use as a simple notepad. Most phones can be configured to beep when a message is received, or just light up an indicator on the display if beeping would be unacceptable. Depending upon the phone and the SIM, you can usually store between 5 and 50 messages. SMS is also used for “internal” messages, such as activating a new mobile telephone, remote programming of telephone numbers into a user's SIM telephone directory, and alerting the user of voicemail.
It is desirable to use SMS messaging to dispatch orders to service providers. In order to further automate and manage dispatch orders to multiple service technicians or providers, gateway software must be developed by which SMS messages may be sent and received to a computer, and displayed in a WINDOWS based application format on a monitor. The gateway software connects the computer to a GSM handset via an interface, such as a data card or special cable, and allows the user to access all the messages currently stored in the phone, send new messages, and even have incoming messages sent straight through to the user's computer (without the phone beeping). Such a gateway would also enable an address book through which messages can be sent to one or multiple technicians on a distribution list, in one action, although the messages are actually sent or transmitted one after the other.